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Sudan Journal of Agricultural Research

Effect of Refrigerated Storage on Chemical and Sensory  Characteristics of Sour Milk (Robe)

Abdel Moneim E. Sulieman, Hamid, A. Dirar, Elamin A. Elkahalifa and Ali O. Ali



Abstract

Robe, a Sudanese traditionally fermented milk product is common in the rural areas of the middle and Western Sudan and is consumed in different ways. In this work, the quality of Robe was investigated through studying of its chemical and sensory characteristics and the effect of refrigerated storage on those characteristics. The analyses included beside the traditional Robe, laboratory-made Robe prepared from pasteurized milk. The quality of fresh milk was also evaluated. The average chemical characteristics of fresh milk were 88.4 + 0.98 % moisture, 0.70 + 0.05 % ash, 3.1 + 0.14 % protein, 3.02 + 0.75 % fat, 11.48 + 0.17 % total solids, 4.6 + 0.1 % lactose, 8.46 + 0.2 % solids-non fat %, 0.16 + 0.02 % titrable acidity and a pH of 6.5 + 0.13.
Robe can be made at the laboratory level using pasteurized milk. The product had a noticeable reduction in the characteristic buttery flavour of traditional Robe, and it has the following chemical composition: 4.2 % protein, 0.34 % fat, 0.84 % ash, 7.8 % total solids, 4.5 % lactose, 7.3 % solids-non fat %, 0.10 % titrable acidity, 0.86 5 ethanol and 0.08 % volatile fatty acid.
The average chemical composition of the traditional Robe was: 91.4 + 0.5 % moisture, 0.88 + 0.02 % ash, 3.86 + 0.2 % protein, 0.83 + 0.8 % fat, 7.65 + 0.1 % total solids, 3.43 + 0.1 % lactose, 8.46 + 0.2 5 % solids-non fat, 0.16 + 0.02 % titrable acidity and a pH of 6.5 + 0.13. Most of these components were higher when Robe was analyzed at the beginning of storage period and decreased with progressing storage period. However, the storage for 7 days significantly affected (p>0.05) all the chemical components of Robe. This storage period, on the other hand, did not significantly (p>0.05) affect sensory attributes like colour, flavour, taste and the overall acceptability, but affected the consistency. The highest score for flavour was after 7 days of storage, while the lowest score was obtained when Robe was organoleptically examined at 0 day. The lowest score for consistency and taste were obtained up to 3 days of storage. All the Robe samples were highly accepted by the panelists.


 

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Sudan Journal of Agricultural Research Vol. 7 (2006) PP. 53-60